Cyclic ortho ester fuel additive

Abstract

The invention relates to liquid hydrocarbons containing cyclic ortho esters as dehydrating dehydrating icing inhibitors and to methods of using the compounds. The liquid hydrocarbons include fuels such aviation fuels, lubricants, hydraulic fluids and hydrocarbon solvents.

Description

BACKGROUND OF THE INVENTION[0001]The invention relates to liquid hydrocarbons such as hydrocarbon fuels, hydraulic fluids, lubricants or solvents, comprising cyclic ortho ester dehydrating icing inhibitors. The hydrocarbon fuels include aviation fuels. Methods of inhibiting ice crystal formation and ice inhibiting compounds are also provided.[0002]Solubility of water in the current context refers to the maximum water concentration which can dissolve in any given amount of hydrocarbons at a specific temperature and air humidity; this is strongly dependent upon the chemical composition of the fuel itself [1, 2].[0003]Dissolved water is often a normal component of liquid hydrocarbons and is vaporised on combustion of hydrocarbon fuels. However, free water can freeze and block fuel or other feed lines. The water can also support microbial growth and contribute to corrosion. There is therefore a need to remove water or reduce the amount of ice crystal formation in liquid hydrocarbons.[00...

AI Technical Summary

Benefits of technology

[0029]The inventors have found that selecting cyclic ortho esters allows water to be scavenged in liquid hydrocarbons using the low levels of acid typically found in the fuels. This means that acid catalysts need not be added to the liquid hydrocarbon, thereby reducing corrosion in, for example, fuel tanks and fuel pipes. The cyclic ortho esters allow the production of water soluble reaction products, such as alcohols and esters Which act as anti-freeze agents to reduce the freezing point of water left in the liquid hydrocarbon. These may also have anti microbial activity. Moreover, the reaction products can be tailored to segregate into the different phases of the fuel. The structure of the cyclic ortho ester also lends itself to being altered to increase the rate of reactivity with water in hydrocarbons, thereby further reducing the amount of acid needing to be present in the liquid hydrocarbon and lending itself to be used in hydrocarbons without sufficient levels of acid present. The ability to scavenge water at the same time as producing reaction products having ice inhibiting properties is particularly advantageous.

Problems solved by technology

However, free water can freeze and block fuel or other feed lines.

However, even if jet fuel enters the fuel tank without free water, this does not prevent its formation.

Free water can starve engines, support microbial growth, contribute towards corrosion and furthermore freeze, risking plugging filters in the aircraft.

The industry has developed equipment and procedures to mitigate these problems, but challenges remain [1, 3].

The aviation industry has identified several problems related to the interaction of FSII and “wet” fuel, which can actually undermine fuel protection.In addition to being hydrophilic, di-EGME is also hygroscopic—this additional characteristic leads to an uptake of atmospheric water during blending operations which affects its solubility in fuel.Di-EGME has a very high water-fuel partitioning ratio: it preferentially dissolves in water.

Unless replenished, the jet-fuel is essentially “stripped” of its protection against icing.The presence of di-EGME in the water contained within the fuel alters interfacial properties, and can impair the performance of filters and monitors.

Particularly, the separation efficiency of filter / coalescers can be compromised [8].

In addition, FSII are toxic at the concentrations required for effective de-icing.

‘Water bottoms’ drained from storage tanks, fuel system sumps and filters inevitably contain higher concentration of di-EGME, creating concerns about the handling and disposal of these wastes [10].

FSII are only mildly irritating, but they are rapidly absorbed by the skin.

Vapours can cause irritation to the eyes and the respiratory system.

Di-EGME is biodegradable in wastewater treatment system; however concentrations found in water bottoms could be high enough to disrupt the microbiological process.

In the environment, the high oxygen demand required for decomposition results in less available oxygen for aquatic organisms [12].

Liquid hydrocarbons, such as aviation fuels present a number of problems for the selection of water scavenging compounds to be used as dehydrating icing inhibitors.

Such low temperatures can dramatically reduce the kinetic energy of participating molecules, to the point that a chemical reaction slows down or effectively stops.

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